1. Field of the Invention
The present invention generally relates to disk units that read information from or write information to a disk medium (hereinafter referred to simply as a disk) by a head moving over the disk medium, and more particularly to a disk unit that increases the positioning accuracy of the head with respect to the disk medium by regulating airflow generated by the rotation of the disk.
Recently, disk units represented by magnetic disk units have been the center of information recording apparatuses. The rapid development and spread of computers in recent years has required disk units to realize larger storage capacity, higher processing speed, lower costs, and downsizing.
A major technical problem in answering these requests is to increase head-positioning accuracy. Factors causing the deterioration of the head-positioning accuracy include both a disturbance synchronous with disk rotation and a disturbance asynchronous with disk rotation. The asynchronous disturbance includes a wind disturbance caused by airflow generated by the mechanical oscillation of a disk unit or by disk rotation.
Lately, the wind disturbance has become an especially major problem. This is mainly due to the following two points. First, a high disk rotation speed for realizing the high-speed operation of a disk unit generates high-speed airflow in the disk unit. Second, with an increase in recording density, head-positioning accuracy has become finer so that airflow has exerted a relatively greater influence.
As described above, the wind disturbance must be reduced to realize the high recording density and high-speed operation of the disk unit.
2. Description of the Related Art
The following two parts are known as means for reducing the wind disturbance employed in a conventional disk unit. The first one is called a shroud. The shroud is a wall having a face perpendicular to a surface of a disk and opposing a part of the peripheral edge of the disk without contact. The shroud regulates airflow generated by disk rotation so that the airflow goes along the face of the shroud, and reduces vibrations generated in a direction other than that of the disk rotation.
The second one is called a spoiler. The spoiler has a given height in a direction perpendicular to the surface of the disk, and extends above the surface of the disk. The spoiler decelerates airflow flowing over the surface of the disk, and regulates the airflow in the extending direction of the spoiler, thus reducing the influence of the wind disturbance on a positioning system.
However, as previously described, the wind disturbance has exerted a greater influence on the head-positioning accuracy lately, thus making it difficult to increase the head-positioning accuracy by individually employing the shroud and spoiler.